The Benfica playmaker claims that his side have the upper hand in Wednesday's Europa League final, believing the Blues are the weakest they have been in many years
The two sides will compete at the Amsterdam ArenA on Wednesday and Aimar showed no hesitation in delivering a withering critique of his Premier League opponents.
"Of course, Chelsea are a big club, but this is not the same team that won the Champions League a year ago," The Mirror quote the 33-year-old as saying.
"This team got knocked out at the group stages. They have not been convincing in Europe or in the Premier League. Since they have inherited a wealthy owner, this is probably the weakest Chelsea team there has been."
The Eagles fell to a 2-1 defeat against Porto on Saturday, with 19-year-old Kelvin scoring a dramatic stoppage time winner, and slipped to second in the Primeira Liga with only a game remaining.
However, despite this setback before the final, Aimar believes the Lisbon-based outfit are primed for Europa League success due to Chelsea's disunity and lack of support for their boss, Rafael Benitez.
"Chelsea are a team that are not behind the coach," he continued. "We can take advantage of the fact they are not at their best and not playing as a team.
"Chelsea lost two great players in Didier Drogba and Michael Essien. Then players who have been so important like John Terry and Frank Lampard are not even getting games!
"It is amazing how much a team can change in 12 months, but that is football."
Chelsea head into the Europa League bout on the back of a 2-1 win over Aston Villa, in which Frank Lampard scored both goals to break the Blues' all-time goalscoring record.